Macoustra Gabriella K, Koppel Darren J, Jolley Dianne F, Stauber Jenny L, Holland Aleicia
School of Earth, Atmosphere and Life Sciences, Faculty of Science, Medicine and Health, University of Wollongong, New South Wales, Australia.
CSIRO Land and Water, Lucas Heights, New South Wales, Australia.
Environ Toxicol Chem. 2021 Jul;40(7):1908-1918. doi: 10.1002/etc.5038. Epub 2021 May 8.
There have been limited studies on the effects of toxicity-modifying factors, such as dissolved organic matter (DOM), on the toxicity of metal mixtures to aquatic biota. The present study investigated the effects of DOM concentration (low, 2.8 ± 0.1 mg C/L; high, 11 ± 1.0 mg C/L) and DOM source (predominantly terrestrial or microbial) on the chronic toxicity of copper (Cu) and nickel (Ni) binary mixtures to the green freshwater microalga Chlorella sp. This was assessed by using a full factorial design of 72-h growth inhibition bioassays. Measured algal growth rate was compared with growth predicted by the concentration addition and independent action reference models. Model predictions were based on concentrations of dissolved metals, labile metals (measured by diffusive gradients in thin films [DGT]), and calculated free metal ions (determined by the Windermere Humic Aqueous Model). Copper/Ni mixture toxicity was synergistic to Chlorella sp. in the absence of added DOM, with evidence of metal concentration-dependent toxicity at low effect concentrations. As DOM concentration increased, the mixture interaction changed from synergism to noninteraction or antagonism depending on the metal speciation method used. The DOM source had no significant effect on mixture interaction when based on dissolved and free metal ion concentrations but was significantly different when based on DGT-labile metal concentrations. Ratio-dependent mixture interaction was observed in all treatments, with increased deviation from the reference model predictions as the mixture changed from Ni- to Cu-dominated. The present study demonstrated that both DOM concentration and source can significantly change metal mixture toxicity interactions and that these interactions can be interpreted differently depending on the metal speciation method used. Environ Toxicol Chem 2021;40:1908-1918. © 2021 SETAC.
关于诸如溶解有机物（DOM）等毒性修饰因子对金属混合物对水生生物毒性影响的研究有限。本研究调查了DOM浓度（低，2.8±0.1mg C/L；高，11±1.0mg C/L）和DOM来源（主要是陆地或微生物来源）对铜（Cu）和镍（Ni）二元混合物对绿色淡水微藻小球藻慢性毒性的影响。这是通过72小时生长抑制生物测定的全因子设计进行评估的。将测得的藻类生长速率与浓度相加和独立作用参考模型预测的生长进行比较。模型预测基于溶解金属、活性金属（通过薄膜扩散梯度[DGT]测量）和计算的游离金属离子（由温德米尔腐殖质水模型确定）的浓度。在没有添加DOM的情况下，铜/镍混合物对小球藻的毒性具有协同作用，在低效应浓度下有金属浓度依赖性毒性的证据。随着DOM浓度的增加，根据所使用的金属形态分析方法，混合物的相互作用从协同作用变为无相互作用或拮抗作用。当基于溶解和游离金属离子浓度时，DOM来源对混合物相互作用没有显著影响，但当基于DGT活性金属浓度时则有显著差异。在所有处理中均观察到比例依赖性混合物相互作用，随着混合物从以镍为主变为以铜为主，与参考模型预测的偏差增加。本研究表明，DOM浓度和来源均可显著改变金属混合物的毒性相互作用，并且根据所使用的金属形态分析方法，这些相互作用的解释可能不同。《环境毒理学与化学》2021年；40：1908 - 1918。© 2021 SETAC。
